Packaging machines of the form-fill-seal type generally involve the formation of an open-ended carton, closing of the bottom end of the carton, filling the carton with a product, and thereafter closing the top end of the carton.
The economics of form-fill-seal packaging machines is based on the throughput of cartons through the packaging machine per unit of time. Techniques for enhancing the throughput of a given packaging machine include the use of dual production lines arranged in side-by-side relationship and employing certain common components of the packaging machine, filling techniques which minimize the loss of product from the carton in the course of the carton filling operation, and others. For any given machine, if the enhancement techniques have been essentially maximized, it may become necessary to look toward minimization of the energy employed in performing one or more, or even the overall, operation of the machine. Any conservation or reduction in the energy employed in the operation of the packaging machine clearly contributes to the economic value of the machine.
In a form-fill-seal packaging machine, a carton blank commonly includes a heat-sealable layer or coating on the outer and inner surfaces of the carton blank. Closure of the bottom of the carton commonly takes the form of prefolding portions of the end side walls of the open bottom end of the carton blank inwardly toward the centerline of the blank, along prescored fold lines. This infolding operation results in a plurality of the infolded portions of the carton overlying one another, at times there being three or more layers of overlying portions of the carton end side walls. To effect closure of the bottom of the blank, these end side wall portions are heated to soften the heat-sealable layer or coating, initially infolded relatively loosely and without interbonding, and thereafter pressed, employing high pressure, into intimate overlying relationship, and cooled to the extent that the overlying end side wall portions are securely bonded to one another to close (seal) the bottom of the carton.